It is known in the art to provide reversible refrigeration devices, known as heat pumps, for heating or cooling the air in a space. It is also known in the art to use a refrigeration circuit for heating a liquid such as water for domestic or other purposes. It has been further proposed to combine the functions of temperature conditioning and water heating in a single refrigeration system, thereby obtaining advantages of both in one unit. For example, U.S. Pat. No. 4,249,390 discloses a system in which water is heated when a space is cooled, and in which, under some conditions, water is heated when the space is heated. The system apparently is not capable of heating water alone, nor of cooling the space without heating water. U.S. Pat. No. 3,916,638 discloses a heat pump which may be used to heat water for domestic purposes when the heat pump is operated to cool a space, or the heat pump can be used to cool a space without heating the domestic water supply. In the space heating mode the auxiliary water supply heat exchanger is bypassed.
A Refrigeration Circuit For Heat Pump Water Heater and Control Therefore are disclosed in my U.S. Pat. No. 4,299,098. The circuit disclosed therein has four operating modes: one for heating a space; one for cooling a space; one for heating the liquid without modifying the air in the space; and one for cooling a space and heating a liquid. As with other refrigeration circuits combining heat pump and water heater operations, the circuit disclosed in my above-cited patent does not include the simultaneous functions of heating the space and heating the liquid.